The invention relates to a yarn draw-off device for a textile machine producing cross-wound bobbins and, more particularly, to a yarn draw-off device having a yarn draw-off roller that can be driven by a single motor and an associated pressure roller which is driven via frictional engagement.
Textile machines producing cross-wound bobbins, in particular open-end spinning machines, have, in the region of their workstations, a yarn draw-off device in each case, which during spinning operation, draws the yarn produced in a spinning mechanism out of the spinning mechanism and conveys it onward at a constant delivery speed in the direction of a winding device, where the yarn is wound to form a cross-wound bobbin.
The yarn draw-off devices consist here either, as described, for example, in German Patent Publication DE 44 32 240 A1 or in German Patent Publication DE 39 17 047 A1, of a drive shaft along the length of the machine, on which a pivotably mounted pressure roller rests in each case in the region of the workstations, or the yarn draw-off devices in each case have a single motor drive. Such yarn draw-off devices driven by a single motor are shown and described, for example, in German Patent Publication DE 101 39 075 A1. These yarn draw-off devices in each case have a relatively large yarn draw-off roller which can be driven by a single motor and a significantly smaller, pivotably mounted pressure roller, which is entrained via frictional engagement by the yarn draw-off roller during spinning operation.
The yarn draw-off roller, which can preferably be reversibly driven by a stepping motor, generally consists here of a rotationally symmetrical diecast or injection-moulded member, in other words consists of a one-pieced cast member, which has an inner fastening hub, an annular outer periphery and a closed connecting disc located in between.
The frequently poor cooling of the yarn draw-off roller drives is disadvantageous in these yarn draw-off devices which have proven successful per se. In other words, overheating of the yarn draw-off roller drives may occur during the spinning process in these known yarn draw-off devices, in particular in the case of unfavourable climatic conditions.